1. Field of the Invention
The invention relates to a guideway for a magnetically levitated railway with a longitudinal stator linear drive having at least two parallel stators and a parts set and a method for making the same.
The invention is particularly concerned with a guideway including a plurality of supports arranged along a given line and adapted to form straight and curved road sections, and stator sections which are mounted on the supports and are arranged along parallel space curve sections associated therewith and are assembled from straight stator end packs and straight middle stator packs arranged therebetween. The stator and stator end packs are laid out in the region of the curved road sections to form outer and inner stator sections in the manner of polygonal lines and are separated from one another by gaps. The stator end packs and the middle stator packs have, as referred to a conceptual space curve lying between space curve sections, a predetermined tooth/groove pitch as well as different xe2x80x9cidealxe2x80x9d lengths, which differ from one another by fractions by a tooth/groove pitch.
The invention is further particularly concerned with a parts set for building guideways of the kind mentioned above and with a method of making a guideway for a magnetically levitated railway with curved and optionally also straight guideway sections, which form at least two tracks, are provided with stators of a longitudinal stator linear motor for each track and have outer and inner track sections in correspondence with their curvature. Two space curves associated with the tracks, at least one first and one second fixedly imposed point and a planning section disposed between these are established, wherein supports and their bearings for the guideway and the stators are arranged along the planning section and wherein the supports are provided with stator packs forming the stators.
2. Description of the Prior Art
Guideways and parts sets of this kind are known (DE 39 28 277 C2, DE 39 28 278 C2). The guideways can be erected with supports of concrete or steel, both on pillars or near to the ground, as required. All pieces of equipment needed to run the magnetically levitated railway are arranged on the supports, which are arranged one after the other in the direction of a previously determined line or route. This applies in particular to the side guide rails needed to guide the vehicles of a magnetically levitated railway and to the reaction rails in the form of stator packs or stator portions, needed to provide the support and drive and whose functional surfaces must lie accurately on space curves predetermined by the routing.
In order to simplify the erection of such a guideway the pieces of equipment, especially the stator packs, consist of linearly extending components, which approximate the space curve involved within curved guideway sections, in the manner of a polygonal line. The deviations from the ideal lines resulting from this are extremely small, since the radii of curvature of the guideways must not be less than about 350 m, for reasons of vehicle construction.
The functional surfaces of the stator packs formed as a rule on the underside of the guideway serve, in conjunction with the support magnets arranged on the vehicle, to create the magnet field between the vehicles and the guideway needed for the contact free levitation technology. The stator packs of a magnetically levitated railway are moreover provided with longitudinal stator linear drive, mostly also on the underside, with teeth and grooves alternating, in which a single or polyphase alternating current traveling field winding is fitted (DE 196 20 221 A1), which serves to generate the traveling field needed for the drive of the magnetically levitated railway. It is usual to provide identical linear drives on the two sides of the vehicle and accordingly to equip each side of a guideway with two parallel stators. Accordingly there are two separate but mechanically fixed together drive systems. In order that these can develop the same thrusts it is necessary that the pitch of the stator grooving is identical and runs synchronously on the two sides, as referred to a conceptual middle line between the two associated space curves, i.e. both stator sides must have identical tooth/groove pitches being the same throughout the whole length of the guideway.
The problem which arises in curved sections is that the space curves of the two stators have different lengths on account of their spacing, i.e. a space curve running along the inside of a curve is shorter that a space curve running along the outside of the same curve. This problem has hitherto been dealt with either by using stator packs of the same lengths and fitting the outer stator packs with greater material gaps than the inner stator packs or the outer stator packs have been made longer than the inner stator packs.
The use of stator packs of the same length is advantageous for constructional and cost reasons but also suffers from disadvantages. These lie in that different sized gaps distort the ideal distribution of the magnetic field of the longitudinal stator for example. Since the individual stator packs are comparatively short (e.g. 1000 mm to 2000 mm), this leads to rapid periodic variations in the forces with which the vehicle is maintained in the levitated state as it traverses the stator packs, with the result that oscillations can be excited in parts of the guideway or of the vehicle. These oscillations may not only affect the life of all elements of the guideway and the vehicle, but can also adversely affect the comfort of the ride and the generation of noise. This problem can be avoided in principle by using longer outer stator packs but this would have the disadvantage that special stator packs would have to be made for all radii of curvature down to about 350 m, which is undesirable for reasons of cost. Accordingly, stator packs with correspondingly matched lengths are associated in practice only with selected ranges of radii of curvature, so that even using this method, large gap widths have to be tolerated at least to some extent.
In addition, with guideways of the kind of interest here, it is desirable for the stator packs composed of individual laminations or sheets to be enveloped in an anti-corrosion coating of one to two millimeters for example, in order to avoid over-rapid corrosion. However, in magnetic terms, this has the consequence that there is a gap imposed by the protective coating in addition to the material gap already mentioned, so that the magnetic gap which is important for the support and traveling properties of the vehicle is still wider than the pure material gap occurring between the adjoining end faces of the stator packs. The material gaps should therefore be kept as small as possible.
The problem of the magnet gap size is intensified when the manufacture of guideways with at least two tracks, e.g. an up and a down track, is involved. In this case the difference between the lengths of the innermost space curve sections and the outermost space curve sections is still greater in curved guideway sections, which leads to the result that, with the use of like stator packs and supports, either an offset between the two tracks has to be accepted or special steps such as deviations from a predetermined tooth/groove pitch for example have to be taken, which further affect the ride and support properties.
It is, therefore, an object of this invention to design the guideway described above such that periodic alterations in the supporting forces during travel of the magnetic levitated railway are largely avoided.
A further object of this invention is to avoid periodic alterations in the supporting forces during travel even when stator packs with only a few different lengths are used.
Yet another object of this invention is to provide a parts set including stator packs, stator end packs and series supports for easily building guideways of the kind specified above and having gaps between the stator packs and stator end packs, which gaps are so small that periodic alterations in the supporting forces during travel of the magnetic levitated railway are largely avoided.
A further object of this invention is to provide a method for making guideways which method is suitable in particular for making guideways with two or more tracks one beside the other.
Yet another object is to provide a method such that stator packs, stator end packs and supports of only a few different sizes can be used without resulting in undesirably large offsets between associated supports of the tracks or in other disturbances.
These and other objects are solved by a guideway, a part set and a method in accordance with this invention.
The guideway of this invention is characterized in that the middle stator packs are so combined with one another in at least one outer or inner stator section under consideration of their different xe2x80x9cidealxe2x80x9d lengths in such a manner that a xe2x80x9cmaterialxe2x80x9d total gap between the stator end packs and the middle stator packs of this stator section has the smallest possible width. The parts set of this invention is characterized in that it contains a plurality of stator packs, stator end packs and series supports a s specified above with respect to the guideway of this invention.
The method according to this invention is characterized in that the spacing between the two fixedly imposed points is so determined that the space curve of that track which adjoins the second fixedly imposed point with an outer track section has a length which corresponds to an integral multiple of a predetermined tooth/groove pitch for the guideway, further in that series supports from the parts set according to this invention are arranged along the currently outer track section, staring from the first fixedly imposed point, while supports which are shorter than the series supports by integral multiples of the tooth/groove pitch are arranged along the currently inner section, wherein the shortening of these supports is so effected that their ends are offset relative to the ends of an associated series support of the outer track section by half a tooth/groove pitch at the most, and in that all supports are fitted with stator packs and stator end packs from the parts set of this invention.
The invention is based on the recognition that large stator gaps and the effects arising therefrom c an be largely avoided in that the guideway is not only assembled from a small number of stator pack types of different lengths, but these stator packs are so combined with one another in each stator section that the currently most favorable gap widths result. This can be achieved with no alteration or only a very slight alteration of the pitch of the stator grooving. This leads to a further advantage, in that the supports to be employed can be standardized and grouped in a few types. In spite of minimal increases in cost for making the different stator types, this leads to substantial advantages in relation to the routing and planning of different road or guideway configurations as well as in the logistics needed for the building of a guideway.
Further advantageous features of the invention appear from the dependent claims.